DENVER -- Rockies left-hander Tyler Anderson, who hasn’t pitched since he was optioned to Triple-A Albuquerque eight days ago, will head to Chicago this week for further medical opinion on his troublesome left knee, manager Bud Black said Sunday.

Anderson missed two weeks in April with left knee inflammation, and his performance didn’t improve in three starts after his return. The club sent him down to correct the issues that led to an 0-3 record and 11.76 ERA in five starts. Since that decision, Anderson and the club have focused on the knee issue.

Anderson, 29, had arthroscopic surgery on the knee during the 2017 season. The problem flared this year during Spring Training and never improved, even with rest and the removal of fluid from the knee early in the regular season.

“The last four or five days, he’s been in consultation with some doctors about his knee,” Black said. “I think he’s going to see a specialist tomorrow in Chicago. We’ll see what this fellow says about Tyler.

“Tyler felt as though he needed it looked at. It got to the point where he truly felt it was affecting his pitching. He wants to gather as many opinions as possible.”

Anderson entered the season with a 3.73 ERA at Coors Field -- fifth-lowest in club history among pitchers with at least 100 innings pitched.